Toner transport mechanism and image forming apparatus

ABSTRACT

Provided is a toner transport mechanism including: a first movable member which is displaced in accordance with an amount of toner in a transport path for transporting toner; a second movable member which is displaced in accordance with a rotation of a transporting member provided in the transport path; and a flag member which is displaced to an acting position where the flag member acts on a sensor and a non-acting position where the flag member does not act on the sensor, in accordance with the displacement of the first movable member and the displacement of the second movable member, the sensor being arranged outside of a duct and detecting an anomaly of the toner transport mechanism.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a toner transport mechanism used in anelectrophotographic image forming apparatus.

Description of the Related Art

Image forming apparatuses, such as copiers, printers and facsimilemachines, which form an image on recording material using anelectrophotographic system may adopt a configuration in which toner suchas untransferred toner having been generated in an image forming processand having become unnecessary without being transferred onto therecording material is transported to and stored in a recovery container.While transportation of unnecessary toner generally involves rotating atransporting member such as a screw or a spring installed on a transportpath to transport the unnecessary toner to the recovery container, tonerleakage sometimes occurs due to damage, an assembly error, or the likeof the transporting member preventing the toner from being normallytransported. Therefore, it is necessary to detect whether thetransporting member is operating normally in order to prevent problemssuch as toner leakage from occurring. Meanwhile, problems occur in whichtoner accumulates on the transport path and toner clogging causestransportation failure, damage to parts, and the like despite thetransporting member operating normally. In consideration thereof, mainlyin order to manage a state of toner inside a recovery container,measures are taken which involve providing a flag member and a sensor ona downstream side on a toner transport path to detect a toner amount, asdescribed in Japanese Patent Application Laid-open No. 2017-21123.

SUMMARY OF THE INVENTION

An unnecessary toner recovery mechanism described in Japanese PatentApplication Laid-open No. 2017-21123 is configured such that, in orderto detect a toner amount inside a recovery container, a flag member isprovided on a downstream side of a transporting member in a tonertransport direction and the flag member is pressed by unnecessary tonerto trip a detection sensor. However, an apparatus configurationdescribed in Japanese Patent Application Laid-open No. 2017-21123represents a configuration which uses a large space inside the recoverycontainer of unnecessary toner, and spatial constraints may arise whenthe apparatus configuration is to be provided at other locations. Forexample, when the same configuration is applied on the toner transportpath with a smaller space than the recovery container, the configurationmay inhibit the transportation of toner and may cause clogging. Inaddition, the configuration described in Japanese Patent ApplicationLaid-open No. 2017-21123 is solely intended to detect a presence orabsence of unnecessary toner, and separately providing failure detectionof the transporting member described earlier requires that a sensor anda detecting member be respectively provided for unnecessary tonerdetection and failure detection, further increasing the number of partsand sizes of installation spaces. Furthermore, since there is a riskthat penetration of toner into a detection sensor portion may causeerroneous detection, a component for sealing a space between the tonertransport path and the detection sensor is generally provided. However,with the configuration described in Japanese Patent ApplicationLaid-open No. 2017-21123, since a connecting portion between the flagmember and the detection sensor is located in a toner transport regionby the transporting member, there is a risk that toner may leak from theconnecting portion and adhere to a detecting portion to impair detectionaccuracy.

An object of the present invention is to provide a technique capable ofrealizing anomaly detection and erroneous detection prevention of atoner transport mechanism with a simple configuration.

In order to achieve the object described above, a toner transportmechanism according to the present invention includes:

a duct which forms a transport path for transporting toner;

a transporting member which is provided in the transport path and whichtransports toner inside the transport path by rotating;

a sensor arranged outside of the duct;

a first movable member which is displaced in accordance with an amountof the toner inside the transport path;

a second movable member which is displaced in accordance with therotation of the transporting member; and

a flag member which is displaced to an acting position where the flagmember acts on the sensor and to a non-acting position where the flagmember does not act on the sensor, in accordance with the displacementof the first movable member and the displacement of the second movablemember.

In order to achieve the object described above, a toner transportmechanism according to the present invention includes:

a duct which forms a transport path for transporting toner;

a transporting member which is provided in the transport path and whichtransports toner inside the transport path by rotating;

a sensor arranged outside of the duct; and

a movable member which is displaced to an acting position where themovable member acts on the sensor and to a non-acting position where themovable member does not act on the sensor, in accordance with an amountof the toner inside the transport path, the movable member beingarranged in an opening which is provided in the duct and which ispositioned above the transporting member.

In order to achieve the object described above, an image formingapparatus according to the present invention includes:

an image forming portion which forms a toner image;

a duct which forms a transport path for transporting toner;

a transporting member which is provided in the transport path and whichtransports toner inside the transport path by rotating;

a sensor arranged outside of the duct;

a first movable member which is displaced in accordance with an amountof the toner inside the transport path;

a second movable member which is displaced in accordance with therotation of the transporting member;

a flag member which is displaced to an acting position where the flagmember acts on the sensor and to a non-acting position where the flagmember does not act on the sensor, in accordance with the displacementof the first movable member and the displacement of the second movablemember; and

a control unit which detects an anomalous state when the acting state bythe flag member lasts more than a prescribed period of time.

According to the present invention, anomaly detection and erroneousdetection prevention of a toner transport mechanism can be realized witha simple configuration.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view of an image forming apparatusaccording to an embodiment of the present invention;

FIG. 2 is a schematic perspective view showing a configuration of atoner transport mechanism according to a first embodiment of the presentinvention;

FIG. 3 is a schematic detailed explanatory diagram of a toner transportmechanism according to the first embodiment of the present invention;

FIGS. 4A and 4B are explanatory diagrams of rotation detection of atoner transport mechanism according to the first embodiment of thepresent invention;

FIGS. 5A and 5B are explanatory diagrams of toner clogging detection ofa toner transport mechanism according to the first embodiment of thepresent invention;

FIG. 6 is a schematic perspective view showing a configuration of atoner transport mechanism according to a second embodiment of thepresent invention;

FIGS. 7A and 7B are explanatory diagrams of toner clogging detection ofa toner transport mechanism according to the second embodiment of thepresent invention;

FIG. 8 is a schematic sectional view of a seal configuration accordingto a modification of the first embodiment of the present invention;

FIG. 9 is a schematic sectional view of a seal configuration accordingto a modification of the first embodiment of the present invention;

FIG. 10 is a schematic sectional view of a seal configuration accordingto a modification of the second embodiment of the present invention; and

FIG. 11 is a schematic diagram of an image forming apparatus and a tonertransport mechanism according to the first embodiment of the presentinvention.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, a description will be given, with reference to thedrawings, of embodiments (examples) of the present invention. However,the sizes, materials, shapes, their relative arrangements, or the likeof constituents described in the embodiments may be appropriatelychanged according to the configurations, various conditions, or the likeof apparatuses to which the invention is applied. Therefore, the sizes,materials, shapes, their relative arrangements, or the like of theconstituents described in the embodiments do not intend to limit thescope of the invention to the following embodiments.

First Embodiment

Hereinafter, a toner transport mechanism and an image forming apparatusprovided with the toner transport mechanism according to an embodimentof the present invention will be described with reference to thedrawings. Examples of image forming apparatuses to which the presentinvention is applicable include image forming apparatuses such ascopiers, printers, and facsimile machines, which form an image onrecording material using an electrophotographic system. In addition,while a transportation object of the toner transport mechanism is mainlyuntransferred residual toner (toner remaining on an image bearing memberwithout being transferred to recording material or an intermediatetransfer member or toner remaining on the intermediate transfer memberwithout being secondarily transferred to recording material),transportation objects also include residual objects other than tonersuch as a scrap of paper and dust.

FIG. 1 is a schematic sectional view showing a configuration of a colorelectrophotographic system image forming apparatus including the tonertransport mechanism according to the present first embodiment. The imageforming apparatus 1 includes four photosensitive drums 2 (2 a, 2 b, 2 c,and 2 d) which are drum-like photosensitive members as image bearingmembers. The photosensitive drum 2 is rotationally driven clockwise inthe drawing by driving means (not shown). In addition, the image formingapparatus 1 includes charging apparatuses 3 (3 a, 3 b, 3 c, and 3 d)which uniformly charge a surface of the photosensitive drum 2 and ascanner unit 4 which irradiates a laser beam based on image informationand which forms an electrostatic latent image on each photosensitivedrum 2.

Furthermore, the image forming apparatus 1 includes developingapparatuses 5 (5 a, 5 b, 5 c, and 5 d) which cause toner including adeveloper to adhere to the electrostatic latent image and develop theelectrostatic latent image as a toner image (a developer image). Inaddition, the image forming apparatus 1 includes drum cleaningapparatuses 6 (6 a, 6 b, 6 c, and 6 d) which remove untransferred tonerremaining on the surface of the photosensitive drum 2 after the tonerimage is transferred to a sheet (recording material) S. In this case,residual toner which cannot be stored in a process cartridge for theremoved residual toner is transported to a toner delivery duct 15 by atoner transport mechanism W and recovered in a toner recovery container16 from the toner delivery duct 15. For example, the toner transportmechanism W is constituted by a toner transport passage, a screw thatrotates inside the toner transport passage, and the like, and isconfigured to be capable of transporting toner from each processcartridge to the toner delivery duct 15. In the image forming apparatus1 according to the present embodiment, the photosensitive drum 2, thecharging apparatus 3, the developing apparatus 5, and the cleaningapparatus 6 are configured as integrated cartridge units whichrespectively form images of different colors (yellow, cyan, magenta, andblack) in accordance with an electrophotographic recording system.

Primary transfer rollers 7 (7 a, 7 b, 7 c, and 7 d) as transferringmeans are in contact with the photosensitive drum 2 via an intermediatetransfer belt 8, and a toner image on the photosensitive drum 2 istransferred to the intermediate transfer belt 8. The intermediatetransfer belt 8 is made taut between a driver roller 9, a tension roller10, and a secondary transfer counter roller 11 and is rotated clockwiseby driving of the driver roller 9. A secondary transfer roller 12provided at a position opposing the secondary transfer counter roller 11via the intermediate transfer belt 8 transfers the toner image havingbeen transferred to the intermediate transfer belt 8 to the sheet S. Inaddition, at a position opposing the tension roller 10 via theintermediate transfer belt 8, a cleaning blade 13 as an intermediatetransfer belt cleaning apparatus removes and recovers untransferredtoner remaining on a surface of the intermediate transfer belt 8.

A paper feeding cassette 17 provided in a bottommost part of theapparatus and a resist roller pair 18 which corrects a skew of the sheetS are installed as feeding and transport means of the sheet S. Due to animage forming portion of each color, the toner image formed on the sheetS via the intermediate transfer belt 8 is fixed gy fixing means 20.During one-side printing, the sheet S to which the toner image is fixedis gueded to a dishcharge transport path 22 by a double flapper 21 astransport path switching means and discharged to a paper discharge tray24 that is sheet stacking means by a paper discharge roller pair 23.

Next, an apparatus operation will be described. A prescribed number ofthe sheets S stacked in the paper feeding cassette 17 are separated oneby one by a feeding roller, transported to a paper feeding/withdrawingroller and the resist roller pair 18, and transported to a contactregion of the intermediate transfer belt 8 and the secondary transferroller 12. A toner image transferred to the intermediate transfer belt 8by the image forming portion of each color is transferred to the sheet Sby the contact region of the intermediate transfer belt 8 and thesecondary transfer roller 12 to form a color image and, subsequently,the sheet S is transported to the fixing means 20. At the fixing means20, heat and pressure are applied to the toner images transferred to thesheet S. Accordingly, the sheet S to which toner images of a pluralityof colors have been fixed is guided by the double flapper 21 to thedischarge transport path 22, passes through the paper discharge rollerpair 23, and is discharged to the paper discharge tray 24. A left door25 can be opened and closed in order to replace the toner recoverycontainer.

A configuration of the toner transport mechanism according to thepresent first embodiment will be described with reference to FIG. 2 toFIGS. 5A and 5B. FIG. 2 is a schematic perspective sectional viewcapturing an overall picture of the toner transport mechanism in theimage forming apparatus 1 according to the present embodiment, of whichan internal structure has been made easily visible by removing a wallportion of the toner delivery duct 15, an outer wall cover of anapparatus main body, and the like on a near side (a side opposite to adirection of an arrow in the diagram). FIG. 3 to FIGS. 5A and 5B areschematic views presenting an enlarged internal section as viewed fromthe sagittal direction shown in FIG. 2. FIGS. 4A and 4B and FIGS. 5A and5B are schematic views for explaining movements of respective componentsinside the toner delivery duct.

As shown in FIG. 2, the toner delivery duct 15 has a transport path 30for transporting toner, and a transport screw 31 as a toner transportingmember and a clogging detecting lever 32 as a first movable member areinstalled inside the transport path 30. In addition, the transport path30 of the toner delivery duct 15 is constituted by a first transportpath 30 a on which toner is transported in an approximately horizontaldirection by the transport screw 31 and a second transport path 30 bwhich is positioned on a downstream side of the first transport path 30a and onto which toner free-falls. Furthermore, an intermediate sensorflag 33 and a detection sensor 34 that is an optical sensor areinstalled at a position never reached by deposited toner in a vicinityof the toner transport path 30. The toner delivery duct 15 includes: ashaft hole 15 a through which the transport screw 31 is inserted; anopening 15 b in which the clogging detecting lever 32 is arranged; anopening 15 c which receives toner transported from the toner transportmechanism W; and an opening 15 d which is communicated with the tonerrecovery container 16. While the toner delivery duct 15 is shown in thediagram with its interior opened, the interior with the exception of theshaft hole 15 a and openings 15 b, 15 c, and 15 d are covered by a walland the toner transport path 30 with an approximately inverted L-shapeis formed from the opening 15 c to the opening 15 d.

The transport screw 31 is capable of rotating in one direction as adriving force from a driving source (not shown) is transmitted theretoand, when the transport screw 31 rotates, a blade portion 31 a of thetransport screw 31 can push toner and transport the toner toward adownstream side in an approximately horizontal direction. The transportscrew 31 has a cam portion 31 b as a second movable member (cam member)at a shaft end on a downstream side in a toner transport direction. Theintermediate sensor flag 33 as a flag member is constantly biased in arotation direction in which a connecting portion (a second pressedportion) 33 d comes into contact with the cam portion 31 b by biasingmeans (not shown) such as a spring. In addition, the intermediate sensorflag 33 has an end flag-shaped portion 33 a on a side opposite to, witha rotating shaft 33 c at center, the connecting portion 33 d connectedto the cam portion 31 b of the transport screw 31. The end flag-shapedportion 33 a can be connected to the detection sensor 34.

The clogging detecting lever 32 is installed above the transport path 30b. The clogging detecting lever 32 has a toner pressed portion 32 a anda lever portion 32 b (first pressing portion), in which case the leverportion 32 b is arranged on an opposite side to the toner pressedportion 32 a across a rotating shaft 32 c. The lever portion 32 b isinstalled in a vicinity of the intermediate sensor flag 33 so as to becapable of pressing a pressed portion 33 b of the intermediate sensorflag 33. The clogging detecting lever 32 is configured to be rotatable(displaceable) such that the lever portion 32 b is displaced in thefollowing manner. That is, in a normal state, the lever portion 32 b ispositioned at a standby position (a non-acting position where the leverportion 32 b does not act on the detection sensor 34). In addition, whenthe toner pressed portion 32 a is pushed upward in a rotation directionA by toner clogging, the lever portion 32 b moves to a position wherethe lever portion 32 b pushes the pressed portion 33 b and causes theintermediate sensor flag 33 to rotate.

A movement of the transport screw 31 will be described with reference toFIGS. 4A and 4B. When receiving a rotational driving force from adriving source, the transport screw 31 rotates in a direction of anarrow B in FIG. 4A. When the transport screw 31 rotates in the directionof the arrow B, the cam portion 31 b at the end also rotates in thedirection of the arrow B and a contact position with the connectingportion 33 d of the intermediate sensor flag 33 on an outercircumferential surface of the cam portion 31 b changes. The cam portion31 b has a cam shape in which a radial dimension of an outercircumferential surface (a second pressing portion) that is a camsurface or, in other words, a distance from a center of rotation to theouter circumferential surface changes in a circumferential direction.Therefore, a change (an increase) in the distance between the contactregion with the connecting portion 33 d and the center of rotation dueto rotation of the cam portion 31 b causes the cam portion 31 b torotate the intermediate sensor flag 33 in a direction of an arrow C asshown in FIG. 4B. At this point, the end flag-shaped portion 33 a of theintermediate sensor flag 33 is displaced to a light-shielding position(an acting portion) where detection light of the detection sensor 34 isshielded or, in other words, a position where an optical path between alight emitting portion and a light receiving portion in the detectionsensor 34 is blocked. Subsequently, the transport screw 31 is furtherrotationally driven and, since the intermediate sensor flag 33 is biasedby biasing means (not shown) such that the connecting portion 33 dmaintains a contact state with the cam portion 31 b, the transport screw31 and the intermediate sensor flag 33 once again return to positionsshown in FIG. 4A. In other words, as long as the transport screw 31continues to be rotationally driven, the intermediate sensor flag 33periodically and repetitively alternates moving (being displaced) to thenon-acting position shown in FIG. 4A and moving (being displaced) to theacting position shown in FIG. 4B.

At this point, the detection sensor 34 detects light shielding(non-light reception) and light transmission (light reception) by theend flag-shaped portion 33 a of the intermediate sensor flag 33. Inaddition, when the transport screw 31 becomes immobile due to damage toor an assembly error of a component and the detection sensor 34 senseslight shielding or light transmission for a certain period of time (whena non-light-receiving state (a non-acting state) or a light-receivingstate (an acting state) lasts more than a prescribed threshold period),the detection sensor 34 detects an anomaly. When anomaly detection isreported from the detection sensor 34, a control unit of the imageforming apparatus stops operation of the apparatus and displays awarning on a display portion (not shown) provided on the apparatus mainbody. In addition to the component damage and the faulty componentassembly described above, conceivable causes of the detection of ananomaly include failure of respective components of a driving sourcethat imparts a driving force to the transport screw 31, and even suchfailures can be detected with the present detection configuration.

FIG. 11 is a schematic diagram of the image forming apparatus and tonertransport mechanism according to the present embodiment. As shown inFIG. 11, a configuration according to the present embodiment includingthe toner transport mechanism W, the toner delivery duct 15, and thedetection sensor 34 corresponds to the toner transport mechanismaccording to the present invention. By the toner transport mechanismwith the above configuration, toner is transported from the imageforming portion which includes the above mentioned process cartridgeinto the toner recovery container. The control unit of the image formingapparatus 1 performs a reporting action for a user which includesdisplaying information for reporting an anomalous state on the displayportion, as a reporting unit, of an operation panel of the apparatus,making an alarm sound for the warning, and so on.

In other words, in failure detecting means according to the presentembodiment, the cam portion 31 b is a component for transmitting andinputting a state of rotation of the transport screw 31 to the detectionsensor 34. In addition, the clogging detecting lever 32 is a componentfor transmitting and inputting a state of circulation (a state ofdeposition) of toner inside the toner transport path formed by the tonerdelivery duct 15 to the detection sensor 34. The failure detecting meansaccording to the present embodiment is configured such that both the camportion 31 b and the clogging detecting lever 32 input respective statechanges thereof to the detection sensor 34 via the intermediate sensorflag 33. In other words, the intermediate sensor flag 33 doubles as acomponent for inputting the state of rotation of the transport screw 31into the detection sensor 34 and a component for inputting the state ofcirculation (the state of deposition) of toner inside the toner deliveryduct 15 to the detection sensor 34.

Seal Configuration

The toner transport mechanism according to the present embodiment adoptsa seal configuration described below in order to prevent false detectionby the failure detecting means or, more specifically, to prevent tonerfrom adhering to the detection sensor 34 and affecting detectionaccuracy.

First, the detection sensor 34 is arranged outside of the toner deliveryduct 15. In other words, in the configuration of the failure detectingmeans, the detection sensor 34 which is a component that desirably doesnot come into contact with toner is arranged outside of a transport pathfor transporting toner. On the other hand, in the configuration fortransmitting and inputting a state inside the toner delivery duct 15 tothe detection sensor 34, the shaft of the transport screw 31 whichsupports the cam portion 31 b and the clogging detecting lever 32 arearranged so as to straddle the inside and outside of the toner deliveryduct 15.

In addition, a space between the transport screw 31 which extends so asto straddle the inside and outside of the toner delivery duct 15 and awall of the toner delivery duct 15 is sealed. Specifically, for example,it is conceivable to minimize a dimensional difference between the shaftof the transport screw 31 and the shaft hole 15 a of the toner deliveryduct 15 or to provide an annular seal member which slides with thetransport screw 31 between the shaft of the transport screw 31 and theshaft hole 15 a. Alternatively, a configuration may be adopted so that ashaft diameter of the transport screw 31 increases on an outer side (aside on which the cam portion 31 b is provided) with respect to alocation inserted into the shaft hole 15 a to reduce leakage of tonerfrom the shaft hole 15 a to the outside. Accordingly, toner transportedinside the toner delivery duct 15 by the transport screw 31 is preventedfrom penetrating, via the shaft hole 15 a, into a space in which isarranged the detection sensor 34 that is the outside the toner deliveryduct 15.

Furthermore, the clogging detecting lever 32 is arranged so as tostraddle the inside and outside of the toner delivery duct 15 via theopening 15 b which is positioned below the detection sensor 34. Althoughthere is a possibility that transported toner may leak out from theopening 15 b, since the detection sensor 34 is positioned above theopening 15 b, leaked toner is unlikely to reach the detection sensor 34.

In addition, the intermediate sensor flag 33 is present between theopening 15 b and the detection sensor 34. Therefore, even if toner leaksout from the opening 15 b, the toner is blocked by the intermediatesensor flag 33 and cannot readily reach the detection sensor 34.

FIG. 8 is a schematic sectional view for explaining a seal configurationaccording to a modification of the first embodiment. In a situationwhere toner leakage from the opening 15 b affects detection by thedetection sensor 34, it is conceivable that the clogging detecting lever32 is already in operation (there is a situation where the cloggingdetecting lever 32 should operate). Therefore, as shown in FIG. 3 andthe like, it is conceivable that a configuration in which a seal is notprovided between the opening 15 b and the clogging detecting lever 32may be adopted without much hindrance. However, as shown in FIG. 8,prevention of false detection by the detection sensor 34 may be enhancedby aligning a position of the rotating shaft 32 c of the cloggingdetecting lever 32 with the opening 15 b and sealing a space between therotating shaft 32 c and the opening 15 b with a seal member 19 whichcomes into sliding contact with the rotating shaft 32 c.

FIG. 9 is a schematic sectional view for explaining a seal configurationaccording to another modification of the first embodiment. Aconfiguration shown in FIG. 9 may be adopted in order to further enhanceprevention of false detection by the detection sensor 34. Specifically,a wall 26 a may be added so as to demarcate a housing space for a sensorhousing portion 26 with the rotating shaft 33 c of the intermediatesensor flag 33 as a boundary, and a seal member 27 which comes intosliding contact with the rotating shaft 33 c may be provided between anopening 26 b of the wall 26 a and the rotating shaft 33 c. According tothis configuration, particularly, toner having leaked outside of thetoner delivery duct 15 can be effectively prevented from going over theseal between the shaft of the transport screw 31 and the shaft hole 15 aof the toner delivery duct 15 and reaching the detection sensor 34.

A movement of the clogging detecting lever 32 will be described withreference to FIGS. 5A and 5B. Normally, the clogging detecting lever 32is fixed at a position shown in FIG. 5A. There may be cases where thetransport path becomes clogged due to a defect of the toner recoverycontainer 16 or the like on a downstream side of the clogging detectinglever 32 and the toner accumulates upward. In such a case, the tonerpressed portion 32 a of the clogging detecting lever 32 is pushed by thetoner and, as shown in FIG. 5B, the clogging detecting lever 32 rotatestoward a side of an arrow D around the rotating shaft 32 c and moves toa clogging detection position. Once the clogging detecting lever 32moves to the clogging detection position, the lever portion 32 b of theclogging detecting lever 32 connects with the pressed portion 33 b ofthe intermediate sensor flag 33 and moves the intermediate sensor flag33 in a direction of an arrow E. Once the intermediate sensor flag 33moves to the position shown in FIG. 5B, the end flag-shaped portion 33 aof the intermediate sensor flag 33 moves to a light-shielding positionof the detection sensor 34 and the detection sensor 34 detects lightshielding. As described earlier, the detection sensor 34 is controlledso as to detect light shielding and light transmission by the endflag-shaped portion 33 a of the intermediate sensor flag 33 and todetect an anomaly upon detecting light shielding (or light transmission)for a prescribed period of time.

Once the clogging detecting lever 32 and the intermediate sensor flag 33are moved by toner clogging to the light-shielding position of thedetection sensor 34 shown in FIG. 5B, the clogging detecting lever 32and the intermediate sensor flag 33 do not further move from theposition regardless of operations and a position of the transport screw31. Therefore, the transport screw 31 and the clogging detecting lever32 can move to the light-transmitting position and the light-shieldingposition of the detection sensor 34 without obstructing each other'smovement.

As described above, a configuration is adopted in which the transportscrew 31 and the clogging detecting lever 32 are installed inside thetoner delivery duct 15 and the detection sensor 34 capable of detectingmovements of the transport screw 31 and the clogging detecting lever 32is installed outside of the toner delivery duct 15. Accordingly, themovement of the transport screw 31 and clogging of the toner transportpath 30 can be detected by one sensor.

Moreover, an application range of the toner transport mechanismaccording to the present invention is not limited to the toner deliveryduct of a color laser beam printer described in the present embodiment.The toner transport mechanism according to the present invention can beapplied to various configurations in an image forming apparatus as longas similar components can be installed in a transport path fortransporting powder.

Second Embodiment

A toner transport mechanism and an image forming apparatus according toa second embodiment of the present invention will be described withreference to FIG. 6 and FIGS. 7A and 7B. In a configuration of the imageforming apparatus according to the second embodiment, since componentsother than the toner delivery duct in the toner transport path are thesame as those in the first embodiment, a description thereof will beomitted. In the components of the toner delivery duct according to thesecond embodiment, characteristic portions that differ from the firstembodiment will be mainly described.

FIG. 6 is a schematic perspective sectional view capturing an overallpicture of the toner transport mechanism according to the secondembodiment of the present invention, of which an internal structure hasbeen made easily visible by removing a wall portion of the tonerdelivery duct 15, an outer wall cover of the apparatus main body, andthe like on a near side (a side opposite to a direction of an arrow inthe diagram).

FIGS. 7A and 7B are schematic views presenting an enlarged internalsection as viewed from the sagittal direction shown in FIG. 6 forexplaining movements of respective components inside the toner deliveryduct 15.

As shown in FIG. 6, the toner delivery duct 15 has the transport path 30for transporting toner, and the transport screw 31 and a cloggingdetecting lever 35 are installed inside the transport path 30. Inaddition, the transport path 30 of the toner delivery duct 15 isconstituted by a transport path 30 a on which toner is transported in anapproximately horizontal direction by the transport screw 31 and atransport path 30 b which is positioned on a downstream side of thetransport path 30 a and onto which toner free-falls. The toner deliveryduct 15 includes: the shaft hole 15 a through which the transport screw31 is inserted; the opening 15 c which receives toner transported fromthe toner transport mechanism W; the opening 15 d which is communicatedwith the toner recovery container 16; and an opening 15 e in which theclogging detecting lever 35 is arranged. While the toner delivery duct15 is shown in the diagram with its interior opened, the interior withthe exception of the shaft hole 15 a and the openings 15 c, 15 d, and 15e are covered by a wall and the toner transport path 30 with anapproximately inverted L-shape is formed from the opening 15 c to theopening 15 d.

The transport screw 31 is capable of rotating in one direction as adriving force from a driving source (not shown) is transmitted theretoand, when the transport screw 31 rotates, the blade portion 31 a of thetransport screw 31 can push toner and transport the toner toward adownstream side in an approximately horizontal direction.

At a connecting portion of the transport path 30 a and the transportpath 30 b, the clogging detecting lever 35 is installed above thetransport screw 31. The clogging detecting lever 35 has a toner pressedportion 35 a and a flag-shaped lever portion (a flag portion) 35 b, andis provided in the toner delivery duct 15 so as to be rotatable around arotating shaft 35 c.

A movement of the clogging detecting lever 35 will be described withreference to FIGS. 7A and 7B.

As shown in FIG. 7A, during normal use in which toner is transportednormally, the clogging detecting lever 35 is at a retracted positionoutside a region in which toner is transported. In other words, in astate where toner is being transported normally, with the exception ofscattering or floating toner, most of the toner transported by arotation of the transport screw 31 is transported by the transport path30 a in a region in which the transport screw 31 rotates. This meansthat the clogging detecting lever 35 arranged above the transport screw31 is at a position deviated from a transport region of toner. In astate where the clogging detecting lever 35 is at the retractedposition, as toner is transported in the transport path 30 by thetransport screw 31, the clogging detecting lever 35 does not obstructmovement of the toner.

As shown in FIG. 7B, there are cases where the transport path 30 bbecomes clogged due to a defect of the toner recovery container 16 orthe like on a downstream side of the clogging detecting lever 35 and thetoner accumulates upward. In such a case, the toner pressed portion 35 aof the clogging detecting lever 35 is pushed by the toner and rotatesaround the rotating shaft 35 c. The lever portion 35 b of the cloggingdetecting lever 35 is installed so as to be positioned in a vicinity ofthe detection sensor 34. The clogging detecting lever 35 is installed soas to maintain, in a normal state, a rotation phase in which the leverportion 35 b is at a light-transmitting position of the detection sensor34 (a non-light-shielding position where detection light of thedetection sensor 34 is not shielded). When the toner pressed portion 35a is pushed up in a direction of an arrow A due to toner clogging on thedownstream side, the clogging detecting lever 35 rotates so as to movethe lever portion 35 b to a light-shielding position where detectionlight of the detection sensor 34 is shielded as shown in FIG. 7B. Oncethe rotation phase where the lever portion 35 b is at thelight-shielding position is assumed, the clogging detecting lever 35does not move from the position (the rotation phase) unless thedeposited toner is removed.

The detection sensor 34 is controlled so as to detect an anomaly when astate where light is shielded by the lever portion 35 b of the cloggingdetecting lever 35 (a non-light-receiving state in which the lightreceiving unit does not receive detection light) continues for a certainperiod of time (lasts more than a prescribed threshold period). Even ina state where toner is being transported normally, depending on anamount of transported toner, it is conceivable that the toner pressedportion 35 a may be pushed by toner and the clogging detecting lever 35may rotate, thereby causing the lever portion 35 b to move to thelight-shielding position instantaneously or for an extremely shortperiod of time. The configuration of detecting an anomaly when thelight-shielding state continues for a certain period of time or more isadopted in order to prevent such irregular light-shielding states frombeing erroneously detected as anomalies.

Seal Configuration

The toner transport mechanism according to the present embodiment adoptsa seal configuration described below in order to prevent false detectionby the failure detecting means or, more specifically, to prevent tonerfrom adhering to the detection sensor 34 and affecting detectionaccuracy.

First, the detection sensor 34 is arranged outside of the toner deliveryduct 15. In other words, in the configuration of the failure detectingmeans, the detection sensor 34 which is a component that desirably doesnot come into contact with toner is arranged outside of a transport pathfor transporting toner.

In addition, the clogging detecting lever 35 is arranged so as tostraddle the inside and outside of the toner delivery duct 15 via theopening 15 e which is positioned above the transport screw 31. Theopening 15 e is positioned above the transport screw 31 and most of thetoner transported by a rotation of the transport screw 31 moves belowthe opening 15 e. In other words, the opening 15 e is provided in aregion where movement of toner does not occur during normal tonertransportation. Since a gap is provided between the opening 15 e and theclogging detecting lever 35 to ensure that movement of the cloggingdetecting lever 35 is not obstructed, there is a possibility that a partof the transported toner may scatter or float and leak out via theopening 15 e. However, the amount of toner which leaks out in such amanner is minimal, and in a situation where toner leakage from theopening 15 e affects detection by the detection sensor 34, it isconceivable that the clogging detecting lever 35 is already in operation(there is a situation where the clogging detecting lever 35 shouldoperate). Furthermore, since the clogging detecting lever 35 is arrangedin the opening 15 e, even if a part of the transported toner scatters orfloats, the toner is blocked by the clogging detecting lever 35 and isprevented from readily reaching the detection sensor 34. Therefore, agap provided between the opening 15 e and the clogging detecting lever35 is not a hindrance and both failure detection and false detectionprevention can be realized with a simple configuration.

FIG. 10 is a schematic sectional view for explaining a sealconfiguration according to a modification of the second embodiment. Aconfiguration shown in FIG. 10 may be adopted in order to furtherenhance prevention of false detection by the detection sensor 34.Specifically, prevention of false detection by the detection sensor 34may be enhanced by aligning a position of the rotating shaft 35 c of theclogging detecting lever 35 with the opening 15 e and sealing a spacebetween the rotating shaft 35 c and the opening 15 e with the sealmember 19 which comes into sliding contact with the rotating shaft 35 c.

As described above, the clogging detecting lever 35 is installed at alocated separated from a transport direction inside the toner deliveryduct 15 in which a transport direction of the transport path 30 changesmidway, and the detection sensor 34 capable of detecting the cloggingdetecting lever 35 is installed outside of the toner delivery duct 15.Accordingly, a situation where toner adheres to the detection sensor 34and impairs detection accuracy can be prevented and, at the same time, asize and the number of components of a seal member can be kept at aminimum.

Moreover, an application range of the toner transport mechanismsaccording to the present invention is not limited to the toner deliveryduct of the color laser beam printer described in the presentembodiment. The toner transport mechanisms according to the presentinvention can be applied to various configurations in an image formingapparatus as long as similar components can be installed in a transportpath for transporting powder.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2017-077494, filed on Apr. 10, 2017, which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. A toner transport mechanism, comprising: a ductwhich forms a transport path for transporting toner; a transportingmember which is provided in the transport path and which transportstoner inside the transport path by rotating; a sensor arranged outsideof the duct; a first movable member which is displaced in accordancewith an amount of the toner inside the transport path; a second movablemember which is displaced in accordance with the rotation of thetransporting member; and a flag member which is displaced to an actingposition where the flag member acts on the sensor and to a non-actingposition where the flag member does not act on the sensor, in accordancewith the displacement of the first movable member and the displacementof the second movable member.
 2. The toner transport mechanism accordingto claim 1, wherein the first movable member has a first pressingportion which presses the flag member so as to displace the flag memberfrom the non-acting position to the acting position when an amount oftoner deposited in the transport path exceeds a prescribed amount. 3.The toner transport mechanism according to claim 2, wherein thetransport path has a first transport path which extends approximatelyhorizontally, and a second transport path which extends downward from adownstream side of the first transport path, and the first movablemember: (i) has, in the second transport path, a pressed portion whichis pressed by toner deposited in the second transport path; (ii) has thefirst pressing portion outside of the duct; and (iii) rotates so as tocreate a state where the first pressing portion presses the flag memberwhen the pressed portion is pressed by the toner.
 4. The toner transportmechanism according to claim 1, wherein the first movable member isarranged in an opening which is provided in the duct and which ispositioned below the sensor.
 5. The toner transport mechanism accordingto claim 1, wherein the second movable member has a second pressingportion which presses the flag member so as to alternately andperiodically displace the flag member to the acting position and thenon-acting position while the transporting member is rotating.
 6. Thetoner transport mechanism according to claim 5, wherein the transportpath has a first transport path which extends approximatelyhorizontally, and a second transport path which extends downward from adownstream side of the first transport path, the transporting member isa screw which extends along the first transport path, and the secondmovable member: (i) is a cam member provided at an end of a shaft of thescrew which extends to the outside of the duct on a downstream side ofthe first transport path; (ii) includes a cam surface serving as thesecond pressing portion; and (iii) rotates due to a rotation of thescrew.
 7. The toner transport mechanism according to claim 1, whereinthe sensor is an optical sensor, and the flag member is displaced to aposition where detection light of the optical sensor is shielded as theacting position and to a position where the detection light is notshielded as the non-acting position.
 8. An image forming apparatus,comprising: an image forming portion which transfers and fixes a tonerimage on recording material to form an image on the recording material;and the toner transport mechanism according to claim 1 which transports,to a recovery container, residual toner not having been transferred tothe recording material.
 9. A toner transport mechanism, comprising: aduct which forms a transport path for transporting toner; a transportingmember which is provided in the transport path and which transportstoner inside the transport path by rotating; a sensor arranged outsideof the duct; and a movable member which is displaced to an actingposition where the movable member acts on the sensor and to a non-actingposition where the movable member does not act on the sensor, inaccordance with an amount of the toner inside the transport path, themovable member being arranged in an opening which is provided in theduct and which is positioned above the transporting member.
 10. Thetoner transport mechanism according to claim 9, wherein the transportpath has a first transport path which extends approximatelyhorizontally, and a second transport path which extends downward from adownstream side of the first transport path, the transporting member isa screw which extends along the first transport path, and the movablemember: (i) is arranged in the opening provided above a shaft hole ofthe screw, in a wall of the duct on a downstream side of the firsttransport path; (ii) has, in the transport path, a pressed portion whichis pressed by toner deposited in the transport path; (iii) has, outsideof the duct, a flag portion which is displaced to the acting positionand to the non-acting position; and (iv) rotates so as to create a statewhere the flag portion is positioned at the acting position when thepressed portion is pressed by the toner.
 11. An image forming apparatus,comprising: an image forming portion which transfers and fixes a tonerimage on recording material to form an image on the recording material;and the toner transport mechanism according to claim 8 which transports,to a recovery container, residual toner not having been transferred tothe recording material.
 12. An image forming apparatus, comprising: animage forming portion which forms a toner image; a duct which forms atransport path for transporting toner; a transporting member which isprovided in the transport path and which transports toner inside thetransport path by rotating; a sensor arranged outside of the duct; afirst movable member which is displaced in accordance with an amount ofthe toner inside the transport path; a second movable member which isdisplaced in accordance with the rotation of the transporting member; aflag member which is displaced to an acting position where the flagmember acts on the sensor and to a non-acting position where the flagmember does not act on the sensor, in accordance with the displacementof the first movable member and the displacement of the second movablemember; and a control unit which detects an anomalous state when theacting state by the flag member lasts more than a prescribed period oftime.
 13. The image forming apparatus according to claim 12, wherein thecontrol unit outputs information for reporting an anomaly when detectingthe anomalous state.
 14. The image forming apparatus according to claim12, wherein the first movable member has a first pressing portion whichpresses the flag member so as to displace the flag member from thenon-acting position to the acting position when an amount of tonerdeposited in the transport path exceeds a prescribed amount.
 15. Theimage forming apparatus according to claim 14, wherein the transportpath has a first transport path which extends approximatelyhorizontally, and a second transport path which extends downward from adownstream side of the first transport path, and the first movablemember: (i) has, in the second transport path, a pressed portion whichis pressed by toner deposited in the second transport path; (ii) has thefirst pressing portion outside of the duct; and (iii) rotates so as tocreate a state where the first pressing portion presses the flag memberwhen the pressed portion is pressed by the toner.
 16. The image formingapparatus according to claim 12, wherein the first movable member isarranged in an opening which is provided in the duct and which ispositioned below the sensor.
 17. The image forming apparatus accordingto claim 12, wherein the second movable member has a second pressingportion which presses the flag member so as to alternately andperiodically displace the flag member to the acting position and thenon-acting position while the transporting member is rotating.
 18. Theimage forming apparatus according to claim 17, wherein the transportpath has a first transport path which extends approximatelyhorizontally, and a second transport path which extends downward from adownstream side of the first transport path, the transporting member isa screw which extends along the first transport path, and the secondmovable member: (i) is a cam member provided at an end of a shaft of thescrew which extends to the outside of the duct on a downstream side ofthe first transport path; (ii) includes a cam surface serving as thesecond pressing portion; and (iii) rotates due to a rotation of thescrew.
 19. The image forming apparatus according to claim 12, whereinthe sensor is an optical sensor, and the flag member is displaced to aposition where detection light of the optical sensor is shielded as theacting position and to a position where the detection light is notshielded as the non-acting position.